1. Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a PDP having an improved bus electrode structure.
2. Discussion of the Background
A PDP displays an image by exciting a phosphor layer with ultraviolet (UV) rays. The UV rays are generated during a glow discharge that occurs by applying a predetermined voltage to electrodes formed in a gas-filled, sealed discharge space.
Generally, the PDP includes facing front and rear panels joined together.
The front panel comprises a front substrate, a plurality of sustaining electrode pairs separated a predetermined distance on the front substrate, a front dielectric layer covering the sustaining electrode pairs, and a protection layer covering the front dielectric layer. Each sustaining electrode pair typically includes a common electrode and a scan electrode, and the common electrodes and the scan electrodes include a transparent electrode and a bus electrode. The bus electrode may be connected to the transparent electrode, and it applies a voltage to the transparent electrode.
The rear panel comprises a rear substrate facing the front substrate, a plurality of address electrodes formed on the rear substrate to cross to the sustaining electrode pairs, a rear dielectric layer covering the address electrodes, a plurality of barrier ribs formed on the rear dielectric layer to define discharge spaces and prevent cross-talk, and a plurality of red, green, and blue color phosphor layers coated in the discharge spaces defined by the barrier ribs.
In a PDP having the above structure, the bus electrode may be formed of a black electrode layer and a white electrode layer. The black electrode layer acts as a shielding film by being disposed close to the front substrate. Japanese Patent Laid-Open Publication No. 2003-187709 discloses technology related to the black electrode layer.
In a conventional bus electrode, average diameters of ruthenium (Ru)—conductive particles, which may form the black electrode layer, silver (Ag)—conductive particles, which may form the white electrode layer, and frit, which is adhesive particles included in the black and white electrode layers, are greater than 5 μm.
However, when the average diameters of the conductive and adhesive particles are greater than 5 μm, the size of pores between the particles increases. Hence, a large number of pin holes may be formed in the bus electrode, resulting in reduced bus electrode density, thereby reducing conductivity by increasing line resistance of the bus electrode. This problem may be severe when the average diameter of the adhesive particles is greater than the average diameter of the conductive particles.
To solve this problem, the bus electrode may be made thicker. However, increasing the thickness increases the material cost, and it may also cause edge-curls, which may occur when both ends of the bus electrode are thicker than a central area, which provides a non-uniform cross-sectional shape.
If the edge-curls are severe enough, a withstand voltage of the front dielectric layer may decrease. Therefore, the thickness of the front dielectric layer may be increased to supplement its withstand voltage. But this requires additional material cost.